1. Technical Field
The present invention relates in general to inlet design for aircraft engines and, in particular, to an improved system, method, and apparatus for designing streamline traced, mixed compression inlets for high speed aircraft engine applications.
2. Description of the Related Art
Air inlet systems for gas turbine powered supersonic aircraft are required to decelerate the approaching flow to subsonic conditions prior to the engine face. Supersonically, this can be done through shock waves or isentropic compression generated externally, internally, or by a mixture of both. Fixed geometry external compression inlets have typically been used for aircraft (e.g., the F-16 and F-18) designed for short excursions to supersonic conditions, due to the relative simplicity and light weight of these designs. Aircraft capable of higher speeds, such as the F-14 and F-15, have employed variable geometry external compression inlets to obtain better engine and inlet airflow matching at low speeds, and higher performance at supersonic speeds.
High altitude supersonic cruise aircraft typically require maximum efficiency at the cruise point to obtain optimum range and payload. At speeds above Mach 2, mixed compression inlet systems become favorable over external compression systems due to reduced drag. Mixed compression inlets have been demonstrated in flight on aircraft such as the A-12, SR-71, D-21, and XB-70. Several other designs have been tested over the past 50 years. All of these mixed compression designs were based on either axisymmetric or two-dimensional compression schemes in order to minimize shock interactions caused by complex, three-dimensional geometry. However, increasing demand for more integrated inlet and airframe concepts has resulted in the need for more exotic inlet aperture shapes. Thus, although present designs and systems are workable, an improved solution would be desirable.